The study, published in the journal Neurology, also found the higher levels of vitamins and fish body oils resulted in less brain shrinkage typical of Alzheimer's disease, while "junk food" diets -- trans-fats found in baked and fried foods, margarine, fast-food and other less-healthy dietary choices -- produced just the opposite result.

Study co-author Maret Traber, a principal investigator with the Linus Pauling Institute at Oregon State University, and scientists from the Oregon Health and Science University in Portland, Ore., said the study involved 104 people, at an average age of 87, with no special risk factors for poor memory or mental acuity.

The researchers tested for 30 different nutrient biomarkers in their blood, and 42 participants also had magnetic resonance imaging scans to measure their brain volume.

"The vitamins and nutrients you get from eating a wide range of fruits, vegetables and fish can be measured in blood biomarkers," Traber said in a statement. "These findings are based on average people eating average American diets. If anyone right now is considering a New Year's resolution to improve their diet, this would certainly give them another reason to eat more fruits and vegetables."

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